Consolidate javascript_dialog_manager.h and javascript_dialog_manager_impl.h

components/app_modal/javascript_native_dialog_factory.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_APP_MODAL_JAVASCRIPT_NATIVE_DIALOG_FACTORY_H_
 #define COMPONENTS_APP_MODAL_JAVASCRIPT_NATIVE_DIALOG_FACTORY_H_
 
 #include "ui/gfx/native_widget_types.h"
 
+namespace app_modal {
+
 class JavaScriptAppModalDialog;
 class NativeAppModalDialog;
 
 class JavaScriptNativeDialogFactory {
  public:
   virtual ~JavaScriptNativeDialogFactory() {}
 
   // Creates an native modal dialog for a JavaScript dialog;
   virtual NativeAppModalDialog* CreateNativeJavaScriptDialog(
       JavaScriptAppModalDialog* dialog,
       gfx::NativeWindow parent_window) = 0;
 };
 
+}  // namespace app_modal
+
 #endif  // COMPONENTS_APP_MODAL_JAVASCRIPT_NATIVE_DIALOG_FACTORY_H_